Artificial lithographic and hectographic stone



UNITED STATES PATENT OFFICE.

WALTER FORBUSH, OF BOSTON, MASSACHUSETTS.

ARTlFIClAL LI THO GRAPHIC AND HECTOGRAPHIC STONE.

SPECIFICATION forming part of Letters Patent N 0. 516,370, dated March13, 1894.

Application filed May 13, 1893- Serial No. 474,135. (No specimens.)

To all whom it may concern:

Be it known thatl, WALTER R. FORBUSH, of Boston, county of Sulfolk,State of Massachusetts, have invented an Improvement in ArtificialLithographic and Hectographic Stone, of which the following is aspecification.

This invention has for its object the production of a cheap, efficient,light, and durable substitute for the expensive and heavy stones nowcommonly used in lithographic work. -As is well known the stonessuitable for lithography are expensive, not only on account of theircomparative scarcity, but also because of the labor necessary to preparethem for use. The stones are very heavy, dificult to handle, and easilydefaced, and when stored in large numbers become dangerous by reason ofthe weight. In the course of my experiments to devise a satisfactorysubstitute for the usual lithographic stone, I have discovered that amixture of gelatinous and earthy matters, with a suitable liquid, makesan artificial lithographic surface which may be used either as a stonefor lithographic work, orhectographically, or a combination of the'twomay be employed if desired, as will be described.

In preparing iny artificial lithographic stone, I take substantiallyequal parts, by volume, of an earthy matter, such as talc, infusorialearth, or soaprstone, preferably in a finely divided condition, andthoroughly incorporate it with a liquid, snchas glycerine,

or water and glycerine, the glycerine prepon-v derating. I then take thegelatinous substance, substantially equal in earthy matter, and whichmay be gelatine, animal or vegetable glue, or albumen, cut it into smallpieces, and add to the liquid and earthy matter, mixed as described,place the ingredients preferably in a water bath, and heat until thegelatinous matter is entirely melted. The mixture is stirred from timeto time to thoroughly intermingle all the ingredients, and when thegelatinous matter has been completely melted the mixture is pouredvolume to the While the earthy matter may be mixed with water or asimilar liquid which does not rapidly evaporate, with good results, Iprefer to use glycerine, either wholly or in part, as the glycerinemaintains the mixture soft and elastic for a long time, and in properworking condition. A separate stone made as described may be used foreach color, as in usual lithographic work, the design being transferredthereto in any suitable ink capable of coagulating the gelatine or othergum,

.taunic and chromic acid, alum, bichromate of potash or ammonia, orsalts of ironbeing some of the substances which will give to the ink therequisite property. The artificial stone can be used hectographically byusing anilines in the ink, or the outline of a design may be made inacid ink, usinganiline colors for the other portions, and when ordinarygreasy lithographic ink is applied to the surface the outlines willtake-up and the aniline colors repel it, so that the design will beproduced upon a sheet of paper in aniline colors and lithographic inkoutline. The printing surface is sufficiently elastic to produce a goodimpression, yet without yielding enough to distortthe design. If it isnot desirable to preserve the design, thesurface of the stone may becleaned by slight grinding with an abrasive substance.

There is practically no limit to the size of the stones made asdescribed, they are very light as compared with the natural lithographicstone, and they are much less expenslve. V

I am aware that thin sheets or films of gelatine have been used asprinting surfaces, and ldo not claim such devices.

I claim- 1. The herein described artificial lithoincorporated with eachother,in substantially to graphic and hectographic stone, composed ofthe proportions specified.

gelatinous and earthy matters, and a liquid, In testimony whereof I havesigned my containing a preponderance of glycerine, in name to thisspecification in thepresence of 5 substantially the proportionsspecified. two subscribing witnesses.

2. The herein described artificial Iitho- 'WALTER R. FORBUSH. graphicand heotographic stone, composed of Witnesses: finely divided infusorialearth,glycerine, and GEO. W. GREGORY,

a gelatinous substance, intimately mixed and JOHN (J. EDWARDS.

